A lot of trees are dying in Africa's Sahel region and new study says climate change caused by humans is to blame. What's more, many tree species are also disappearing.
在非洲撒赫勒地区，很多树木正在不断死亡，最新研究表明，导致树木死亡的真正原因是气候变化。 更可怕的是，伴随着树木的死亡很多树种也在灭绝。
The study appears in the Journal of Arid Environments. Climate change scientist Patrick Gonzalez led the research on six countries. At the time of the study, Gonzalez was a visiting scholar at the Center for Forestry at the University of California at Berkeley.
这项研究结果发布在美国《干旱环境》杂志上。 气候变化科学家帕特里克.冈萨雷斯在六个国家分别做过这个实验。 在做这项研究时，冈萨雷斯还是伯克利市加州大学林业中心访问学者。
"We conducted our research in the African Sahel, an arid region on the edge of the Sahara where people depend on trees for survival. And the Sahel has experienced the most severe drought in the world in the modern rainfall measurement record," he said.
“我们在撒哈拉沙漠边境上的撒赫勒地区开展实验，那里很多人依靠种植树木生存。 那时候，我们所测到的降雨量显示，撒赫勒地区正在遭受世界上最严重的旱灾。”
The research shows that during the 20th Century rainfall in the Sahel dropped between 20 and 30 percent.
研究结果表明，仅在20世纪，撒赫勒地区的降雨量就减少了百分之二十到三十。
"One in six trees died in the last half of the 20th Century and, second, one in five tree species disappeared locally. And then third, together these changes shifted vegetation zones southward toward areas of more rainfall," he said.
“在二十世纪后五十年，每六颗树中就有一颗死亡，五个树种就有一种灭绝。 更严重的是，这二者共同作用导致雨量较多的南部植被区域受到影响。”他说。
Possible causes of the vegetation shift include declining rainfall, growing human population and decreasing soil fertility.
南部植被减少有以下几种可能因素：降雨量减少，人口增加，以及土壤肥力削减。
"Our statistical comparison showed that climate outweighed the other factors. So, climate change was the main cause of the loss of the trees. Closer to the Sahara you have arid zone trees like Acacia with thorns. Very dry trees. And then as you move farther south towards the Equator, you have species that have fruits and hardwood and species that require more rainfall, that require moister conditions," he said.
“调查数据显示，气候变化对植被影响最大。 也就是说，造成树木死亡的主要原因是气候改变。 在靠近撒哈拉沙漠的干旱地区，比如，带刺的阿拉伯树胶。 非常耐干旱的树种。 向靠近赤道的南部推移，就有果树，阔叶树等等对降水需求量更大的树种，也就需要更潮湿的环境。”他说。
The study blames the climate change in the Sahel on motor vehicle and power plant emissions and other human activity over the years.
这项研究将撒赫勒地区气候改变归咎于多年来的汽车尾气排放，发电厂污染气体排放，以及其他人类活动。
Gonzalez described conditions near the Sahara as long-term land degradation.
冈萨雷斯表示撒哈拉地区的情况将导致长期的土地退化。
"So we actually are showing a form of desertification. Desertification is land degradation. We're not showing a shift of the sands of the Sahara, but what we are showing is a degradation far south of the Sahara within the Sahel within the Sudan, within Guinea. Those are the zones south of the Sahara," he said.
“其实，这就是一个沙漠化的过程。 沙漠化也叫做土地退化。 值得注意的是，我们现在所说的不是撒哈拉沙漠土质的改变，而是撒哈拉沙漠南部地区撒赫勒，苏丹，几内亚境这三个国家境内的土地退化。 这些国家都位于撒哈拉沙漠南部。”他说。
Local populations in the region have roots going back more than a thousand years and relocating is not an option. Indigenous people are adapting to climate change, for example, by caring for and pruning small trees until they're mature. Such a practice can help double tree density in a field.
当地人民在这里生活已经有超过一千年的时间，因此，迁移是不可行的。 当地的人们正在学着适应气候变化，比如说，在树苗成长为大树之前，一直保护修剪树苗。 这样可以增加树木的密集度。
However, Gonzalez said local populations cannot address climate change by themselves. He says the international community must act.
然而，冈萨雷斯表示仅仅依靠当地群众并不能解决气候变化问题。 他说，国际组织必须立刻行动起来。
"The Intergovernmental Panel on Climate Change – that's the top scientific panel that examines climate change and I sit on that panel – has shown that we, in the United States, and other industrialized nations have it in our power using current technologies and practices to avert more drastic impacts around the world by reducing our greenhouse gas emissions," he said.
“政府间气候变化委员会-考核气候变化的最高级组织，我也是其中一员 -表示美国和其他工业化国家已经采取最新科学技术 来减少温室气体排放，从而避免产生更严重的后果。”他说。
Gonzalez was joined in the research by Compton Tucker, senior earth scientist at NASA's Goddard Space Flight Center and Hamady Sy, Mauritania's country representative at the Famine Early Warning Systems Network. Both NASA and the U.S. Geological Survey provided funding for the study.
冈萨雷斯也加入了美国宇航局戈达德太空飞行中心的资深地球学者塔克.康普顿和饥荒预警系统网络毛里塔尼亚国家代表哈马德.萨里的共同研究。 美国宇航局和美国地质调查局也都在为这项研究提供资金支持。
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